Abstract: The authors collected and analyzed three rainwater samples in Shenzhen in April and four rainwater samples in a rural area of Taian in July, 2007. The ion species in PM_2.5 and PM₁₀ concentrations were measured to get the influence of washout process of particles on ion concentrations in rainwater. Compared to that in Taian, the rainwater in Shenzhen showed higher ion concentrations and stronger acidity. The washout process made a more important contribution to ion concentrations in rainwater in Taian than in Shenzhen, because Taian had a more serious air pollution. The washout process of particles was very important. The scavenging ratios of Ca²⁺ and Mg²⁺ in PM²⁺ were high for Ca²⁺, Mg²⁺ mostly existed in coarse particles. NO^-₃, NH⁺₄, Cl^- and K⁺ mainly existed in fine particles and had smaller scavenging ratios. SO₂ and H₂SO₄ contributed a lot to the concentration of SO^2-₄ in rainwater and therefore SO^2-₄ had a high scavenging ratio.

Key words: precipitation, particles, washout, scavenging ratios

摘要： 采集并分析了2007年深圳4月份3场降水和泰安郊区7月份4场降水离子组成, 并测定了观测期间PM_2.5和PM₁₀中离子组成，研究颗粒物在云下冲刷过程对雨水中离子组分的影响。同泰安郊区相比，深圳雨水中主要离子浓度较低，雨水酸化较严重，云下冲刷对雨水中主要离子贡献较小。颗粒物的云下冲刷过程比较重要，PM₁₀中Ca²⁺和Mg²⁺清除比较大，NO^-₃,NH⁺₄和Cl^-的清除比较小，气体SO₂,H₂SO₄对雨水中SO^2-₄的贡献使SO^2-₄具有较高的清除比。

关键词: 降水, 颗粒物, 云下冲刷, 清除比